#12274: use proper escaping for % in IDLE config.
diff --git a/Lib/idlelib/config-main.def b/Lib/idlelib/config-main.def
index 5ddd098..9546e2b 100644
--- a/Lib/idlelib/config-main.def
+++ b/Lib/idlelib/config-main.def
@@ -46,8 +46,8 @@
 [General]
 editor-on-startup= 0
 autosave= 0
-print-command-posix=lpr %s
-print-command-win=start /min notepad /p %s
+print-command-posix=lpr %%s
+print-command-win=start /min notepad /p %%s
 delete-exitfunc= 1
 
 [EditorWindow]